bpo-32912: Replace a DeprecationWarning with a SyntaxWarning (GH-9652)

for invalid escape sequences in string and bytes literals.

2 files changed, 11 insertions, 2 deletions

diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index 84e8c78..e1d88ef 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -559,8 +559,11 @@ escape sequences only recognized in string literals fall into the category of
 unrecognized escapes for bytes literals.
 
    .. versionchanged:: 3.6
-      Unrecognized escape sequences produce a DeprecationWarning.  In
-      some future version of Python they will be a SyntaxError.
+      Unrecognized escape sequences produce a :exc:`DeprecationWarning`.
+
+   .. versionchanged:: 3.8
+      Unrecognized escape sequences produce a :exc:`SyntaxWarning`.  In
+      some future version of Python they will be a :exc:`SyntaxError`.
 
 Even in a raw literal, quotes can be escaped with a backslash, but the
 backslash remains in the result; for example, ``r"\""`` is a valid string
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index bd3283c..e522add 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -107,6 +107,12 @@ Other Language Changes
   and :keyword:`return` statements.
   (Contributed by David Cuthbert and Jordan Chapman in :issue:`32117`.)
 
+* A backslash-character pair that is not a valid escape sequence generates
+  a :exc:`DeprecationWarning` since Python 3.6. In Python 3.8 it generates
+  a :exc:`SyntaxWarning` instead.
+  (Contributed by Serhiy Storchaka in :issue:`32912`.)
+
+
 New Modules
 ===========